Deposition of Thermal Solar Absorber Film by Spray Coating Technology

This research experimentally investigates influences of spray coating process on the solar absorptance, thermal emittance and thermal collection efficiency of the selective absorbing film. Results show that thickness of the selective absorbing film has a strong effect on the absorptance and the emittance of the selective absorbing film. The absorptance up to 93% while the emittance down to 65% can be achieved at a film thickness of 3.3 μm. Properly selection of the film thickness results in the optimum composition of the absorptance and the emittance and thus the optimum thermal collection efficiency of solar energy. Results also show that higher median diameters of the spray can increase the absorptance and reduce the emittance, thus has a positive effect on the thermal collection efficiency. It is due to lower evaporation of the solvent and thus more capability for the redistribution of carbon particles as deposited onto a substrate.